US6150935A - Fire alarm system with discrimination between smoke and non-smoke phenomena - Google Patents

Fire alarm system with discrimination between smoke and non-smoke phenomena Download PDF

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Publication number
US6150935A
US6150935A US08/853,605 US85360597A US6150935A US 6150935 A US6150935 A US 6150935A US 85360597 A US85360597 A US 85360597A US 6150935 A US6150935 A US 6150935A
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United States
Prior art keywords
detector
smoke
condition
detectors
signal
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Expired - Lifetime
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US08/853,605
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English (en)
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Donald D. Anderson
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Pittway Corp
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Pittway Corp
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Priority to US08/853,605 priority Critical patent/US6150935A/en
Assigned to PITTWAY CORPORATION reassignment PITTWAY CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: ANDERSON, DONALD D.
Priority to EP98303622A priority patent/EP0877347B1/de
Priority to DE1998621671 priority patent/DE69821671T2/de
Priority to JP16578798A priority patent/JP3973762B2/ja
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    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/103—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device
    • G08B17/107—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device for detecting light-scattering due to smoke
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
    • G08B29/18—Prevention or correction of operating errors
    • G08B29/185—Signal analysis techniques for reducing or preventing false alarms or for enhancing the reliability of the system
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
    • G08B17/11—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using an ionisation chamber for detecting smoke or gas
    • G08B17/113—Constructional details

Definitions

  • the invention pertains to fault detection of electrical signals received from ambient condition sensors. More particularly, the invention pertains to processing apparatus and methods for minimizing false alarms due to non-smoke variations in electrical signals indicative of ambient conditions such as smoke or fire.
  • a control unit associated with the system Upon receipt of inputs from one or more of the detectors of the system, a control unit associated with the system is able to make a determination as to whether or not a fire condition is present in one or more regions of interest. A variety of techniques have been used in the past for the purpose of making this determination.
  • Sensors of smoke such as photoelectric smoke detectors or ionization-type smoke detectors are intended to provide outputs indicative of sensed levels of ambient smoke.
  • Environmental noise such as dust particles or insects which may enter the respective detector can produce variations in output signals from the sensors which are not in any way correlated with the presence of smoke. These noise outputs can produce false alarms if the sensitivity of the respective detector is high enough. Such false alarms are undesirable.
  • Photoelectric smoke sensors used for early warning typically use a light source and a light sensitive receiver.
  • the design and placement of the light source, receiver, and baffling are such that no significant light from the source normally reaches the receiver unless smoke or other particles are present in the area of the light beam. If smoke or other particles are present in this area, they will scatter the light photons, and cause some of the light to reach the receiver.
  • non-early warning smoke detection systems the density of smoke required at a sensor to cause an alarm is relatively large compared to the density of dust, fibers and other non-smoke particles normally existing in the environment, therefore these systems are not susceptible to false indications caused by such particles.
  • the signals given by low levels of smoke may be comparable to that given by non-smoke airborne particles in the environment that this type of system is typically used.
  • filters were used to remove non-smoke particles in the air present in the smoke sensors.
  • the presence of a filter usually requires that the sensor include a fan or other means to draw air through the filter.
  • the mechanical fans and filters used in prior art detectors are expensive, subject to failure, and require regular maintenance.
  • detectors which can be used in early warning systems without requiring the presence of fans or filters. Preferably minimizing false indications could be accomplished without significantly increasing the expense of such systems while avoiding any need to incorporate additional mechanical components.
  • a fire detection and alarm system in accordance with the present invention includes a control unit and multiple early warning smoke sensors. Each of these smoke sensors measures the density of smoke particles in its area. Each of the sensors then sends a signal to the control unit which is an electrical indication of that smoke density. The control unit processes the signals from at least some of the sensors and determines if an alarm condition exists.
  • the system requires that at least two smoke sensors be installed in each room or enclosed space.
  • the probability that a fiber particle, large enough to cause a false reading, will enter a single smoke sensor is small, but significant.
  • the probability that such a particle will enter two sensors at the same time is so small as to be insignificant.
  • control unit When the control unit identifies a signal from a first sensor that could be indicative of smoke alarm, it then analyzes the signal and determines if the reading could also be indicative of fiber particle. If the reading from the first sensor could be indicative of a fiber particle, the control unit then analyzes a reading from a second detector known to be in the same room.
  • control unit will provide an indication that the signal at the first sensor has been caused by a fiber particle or some other non-smoke phenomenon. A maintenance or trouble signal can then be generated.
  • FIG. 1 is a block diagram of an alarm system
  • FIG. 2 is a block diagram of a detector usable with the alarm system of FIG. 1;
  • FIG. 3 is a sectional view of a prior art photoelectric detector
  • FIG. 4 is a sectional view of a photoelectric detector
  • FIG. 5 is a schematic representation of a detector containing a fibrous element
  • FIG. 1 illustrates a block diagram of a system 10 in accordance with the present invention.
  • This system 10 includes a control unit 12, which can be implemented with a programmable processor 14 and a storage unit 16.
  • the storage unit 16 can include both control programs and data storage regions for use by the processor 14.
  • the control unit 12 is coupled by a bidirectional communication link 20 to a plurality of ambient condition sensors or detectors generally indicated at 22.
  • the members of the plurality 22, such as sensors 22a, 22b . . . 22n are intended to detect a particular ambient condition in an adjacent region.
  • the system 12 can also include an operator display unit with an output visual display device 15a and an operator control or input device such as keyboard 15b.
  • the control unit 12 also includes a plurality of system outputs.
  • the outputs can be used to activate audible or visual alarms.
  • the unit 12 can be coupled to ventilation or air handling systems in the building so as to control smoke migration.
  • detectors include ionization-type or photoelectric-type smoke detectors. Temperature sensors as well as other types of ambient condition sensors could be used in the system 10 in accordance with the present invention.
  • the system 10 is intended to monitor one or more regions, for example regions R1, R2 which might or might not be contigious.
  • regions R1, R2 which might or might not be contigious.
  • Two or more detectors 22-1, 22-2 . . . 22-k are located in region R1.
  • Detectors 22-1'. . . 22-k' are located in region R2.
  • the regions R1, R2 can be substantially closed rooms for example.
  • FIG. 2 is a block diagram representation of a detector 22i useable with the system 10.
  • the detector 22i includes a sensor element 30.
  • the element 30 is intended to sense a particular ambient condition, such as smoke, temperature, infrared radiation or the like and it generates an electrical system indicative thereof on a line 32.
  • output from the sensor 30, on the line 32 is coupled to a local detector control element 40.
  • the control element 40 could be implemented with either digital or analog circuitry. If in digital form, the control element 40 could be implemented as either hard wired logic or could incorporate a programmed microprocessor.
  • the control element 40, via interface circuitry 42 is capable of carrying on bidirectional communication with the system control unit 12, via the communication link 20.
  • a method in accordance with the present invention could be implemented in either the system control unit 12 or the detector local control element 40 without limitation.
  • Implementation can be by either hardwired circuitry or by means of a programmed microprocessor also without limitation.
  • FIG. 3 illustrates in cross-section, a prior art photoelectric chamber PA-10.
  • This chamber includes a housing PA-12 with an internal sensing volume PA-14.
  • a light emitting source, PA-16 is carried on the housing and oriented to emit a beam of light PA-18 into the internal light sensing region PA-14. As is illustrated in FIG. 3, the emitted light beam PA-18 exhibits a somewhat conical expanding shape as it traverses the region PA-14. The light beam PA-18 is directed toward and absorbed on the housing PA-12.
  • a photoelectric sensor PA-20 Offset from the axis of the beam PA-18 is a photoelectric sensor PA-20.
  • the sensor PA-20 is oriented such that light from the beam PA-18 which has been scattered by particulate matter in the volume PA-14 will be incident thereon thereby generating an output electrical signal.
  • Elements PA-22 and PA-24 limit the amount of light which can fall upon the sensor PA-20.
  • the effective sensing light volume which is the region in which smoke particles can be detected.
  • the geometry of the chamber PA-10 is on the order of 0.064 cubic inches.
  • FIG. 4 is a cross-sectional drawing of a smoke sensing chamber 30 of a representative smoke detection device such as 22i in accordance with the present invention.
  • the housing 30 could, for example, have a diameter on the order of three inches or less.
  • a housing with a diameter on the order of two and one-half inches or less could be used.
  • the light source is pulsed to cause it to emit a short pulse of light at periodic intervals (every few seconds).
  • a lens 30-2 focuses the light into a small but intense beam 30-3.
  • the light beam 30-3 continues through the detector chamber until it strikes a light trap 30-4 at the opposite end of the chamber.
  • the light trap absorbs most of the light, and reflects a small amount away from the central chamber area.
  • source 30-1 in combination with the lens 30-2 will produce a beam 30-3 having an effective beam or light sensing volume on the order of 0.0022 cubic inches.
  • This beam volume is on the order of 3% that of prior art detectors.
  • dust particles are large compared to the diameter and volume of the beam 30-3.
  • the dimensions of light beam 30-3 as well as those of the sensing beam volume are smaller than a typical distance between ambient dust particles. As described subsequently, this reduced volume makes the detector 30 less likely to produce dust induced output signals which appear to be due to the presence of smoke.
  • Such smoke detectors can also include a collector or baffle of scattered radiant energy 30-8.
  • ESV Effective Scattering Volume
  • Smoke particles are small and numerous compared to dust and fiber particles, which are relatively large and sparse.
  • the ESV is designed so its dimensions are small relative to the typical distance between large airborne dust particles, yet large relative to the distance between smoke particles in a true fire. In this way is very unlikely that more than one large dust particle (large enough to give a significant signal at the sensor 30-7) will occupy the ESV at the same time. Since the airborne particles are in constant motion, the occasional dust particles will cause a transient signal at the sensor 30-7 as the dust particles pass in and out of the ESV. Smoke particles generate a relatively constant signal at the sensor because many are in the ESV, and as some pass out of the ESV, others move in.
  • Fiber particles may perform similarly to dust (i.e. pass through the ESV and cause only a transient signal). However, since they are very long in one dimension, it is possible that one end of the fiber may touch a surface in the sensor and the other end encroach on the ESV. This situation is illustrated in FIG. 5. Fiber particle F has entered the detector illustrated therein.
  • the fiber F Since the fiber F is not airborne, it may remain in this position for a long period of time and provide a constant signal to the sensor 30-7 and control unit 12. Since fiber particles are typically very large compared to smoke particles, their presence can cause a false alarm unless steps are taken to detect their presence.
  • the present system and method discriminate between smoke and fiber particles.
  • the control processor 14 via software first analyzes previous measurements stored in memory 16 for that detector. If the previous stored readings exhibit a profile indicative of a fire condition, such as a relatively gradual increase over time, the signal from that detector is indicative of smoke and an alarm is indicated by and at the control unit 12. It will be understood that other fire profiles can be used. For example, the slopes of the output signals from the first detector can be compared to a preset value. Alternately, pattern recognition techniques could be used without departing from the spirit and scope of the present invention.
  • the control unit 12 analyzes the signals received from a second detector known to be located in the same room or physical space.
  • the control unit 12 will examine the output from detector 22-1, not detectors 22-1' or 22-k'. If no significant signal, even a very low signal, is received from detector 22-1, (which is in the same room R1), for a predetermined time period, this is further evidence that the signal at the detector 22-k is caused by a fiber particle and not smoke. If this lack of signal at the second detector 22-1 occurs, the control unit 12 does not indicate an alarm but instead indicates on its display 15a that a fault condition exists in the detector 22-k and that detector must be checked or cleaned. If instead, during the predetermined time period, a small analog signal is being sent from the second detector 22-1, the control unit 12 will indicate an alarm condition for the first detector 22-k.
  • a preferred analysis time is in a range of 5 to 60 seconds.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Fire Alarms (AREA)
  • Fire-Detection Mechanisms (AREA)
  • Alarm Systems (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
US08/853,605 1997-05-09 1997-05-09 Fire alarm system with discrimination between smoke and non-smoke phenomena Expired - Lifetime US6150935A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US08/853,605 US6150935A (en) 1997-05-09 1997-05-09 Fire alarm system with discrimination between smoke and non-smoke phenomena
EP98303622A EP0877347B1 (de) 1997-05-09 1998-05-08 Brandmeldeanlage
DE1998621671 DE69821671T2 (de) 1997-05-09 1998-05-08 Brandmeldeanlagen
JP16578798A JP3973762B2 (ja) 1997-05-09 1998-05-11 警報システム

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US08/853,605 US6150935A (en) 1997-05-09 1997-05-09 Fire alarm system with discrimination between smoke and non-smoke phenomena

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Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10046992C1 (de) * 2000-09-22 2002-06-06 Bosch Gmbh Robert Streulichtrauchmelder
US20040189461A1 (en) * 2002-09-19 2004-09-30 Tice Lee D. Multi-sensor device and methods for fire detection
US6879253B1 (en) * 2000-03-15 2005-04-12 Siemens Building Technologies Ag Method for the processing of a signal from an alarm and alarms with means for carrying out said method
US20090009345A1 (en) * 2007-07-03 2009-01-08 Conforti Fred J System and method for an optical particle detector
US20100039645A1 (en) * 2007-03-09 2010-02-18 Xtralis Technologies Ltd Method and system for particle detection
US20100085199A1 (en) * 2008-10-03 2010-04-08 Universal Security Instruments, Inc. Dynamic Alarm Sensitivity Adjustment and Auto-Calibrating Smoke Detection
EP2244236A1 (de) 2009-04-23 2010-10-27 Honeywell International Inc. Ansaugender Rauchmelder mit variabler Geschwindigkeit
US20110018726A1 (en) * 2008-10-03 2011-01-27 Universal Security Instruments, Inc. Dynamic Alarm Sensitivity Adjustment and Auto-Calibrating Smoke Detection
US8378808B1 (en) 2007-04-06 2013-02-19 Torrain Gwaltney Dual intercom-interfaced smoke/fire detection system and associated method
US8395501B2 (en) 2010-11-23 2013-03-12 Universal Security Instruments, Inc. Dynamic alarm sensitivity adjustment and auto-calibrating smoke detection for reduced resource microprocessors
RU2487416C1 (ru) * 2011-10-31 2013-07-10 Сергей Иванович Бурдюгов Адаптивный способ пожарной сигнализации
US20140062705A1 (en) * 2012-08-30 2014-03-06 Honeywell International Inc. Multilevel Signaling System and Method
US20140145851A1 (en) * 2011-02-21 2014-05-29 Fred Conforti Apparatus and method for detecting fires
US9934672B2 (en) * 2015-09-24 2018-04-03 Honeywell International Inc. Systems and methods of conserving battery life in ambient condition detectors
US20190066464A1 (en) * 2017-07-05 2019-02-28 Oneevent Technologies, Inc. Evacuation system
US11176796B2 (en) 2018-07-13 2021-11-16 Carrier Corporation High sensitivity fiber optic based detection
US11340172B2 (en) 2018-07-13 2022-05-24 Carrier Corporation Enhanced robustness for high sensitivity fiber optic smoke detection
US11875664B2 (en) 2021-06-04 2024-01-16 Smart Cellular Labs, Llc Integrated smoke alarm communications system
US11936489B2 (en) 2021-02-02 2024-03-19 True Manufacturing Co., Inc. Systems, methods, and appliances that enable regional control of refrigeration appliances
US11948439B2 (en) 2018-07-13 2024-04-02 Carrier Corporation High sensitivity fiber optic based detection

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EP2053574B1 (de) * 2007-10-25 2014-11-12 Securiton AG Rauchmelder mit Teilchenunterdrückung
US8994562B1 (en) 2011-12-06 2015-03-31 Shane Daniel Boat monitoring systems and methods
CN102521943A (zh) * 2012-01-10 2012-06-27 浙江宇安消防装备有限公司 一种便携式逃生器材存放箱和小区智能消防预警集成装置
CN104332037B (zh) * 2014-10-27 2017-02-15 小米科技有限责任公司 告警检测的方法及装置
DE102016209052A1 (de) * 2016-05-24 2017-11-30 Hekatron Vertriebs Gmbh Verfahren zur Erkennung von Rauch und Gefahrenmelder

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US5172096A (en) * 1991-08-07 1992-12-15 Pittway Corporation Threshold determination apparatus and method
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US5557262A (en) * 1995-06-07 1996-09-17 Pittway Corporation Fire alarm system with different types of sensors and dynamic system parameters
EP0760464A1 (de) * 1995-09-01 1997-03-05 Pittway Corporation Vorrichtung und Verfahren zur Vorverarbeitung von Signalen

Patent Citations (7)

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US4611197A (en) * 1985-02-19 1986-09-09 Sansky Michael J Malfunction-detecting status monitoring system
US4812819A (en) * 1987-04-13 1989-03-14 The United States Of America As Represented By The United States Department Of Energy Functional relationship-based alarm processing system
US4916432A (en) * 1987-10-21 1990-04-10 Pittway Corporation Smoke and fire detection system communication
US5172096A (en) * 1991-08-07 1992-12-15 Pittway Corporation Threshold determination apparatus and method
US5483222A (en) * 1993-11-15 1996-01-09 Pittway Corporation Multiple sensor apparatus and method
US5557262A (en) * 1995-06-07 1996-09-17 Pittway Corporation Fire alarm system with different types of sensors and dynamic system parameters
EP0760464A1 (de) * 1995-09-01 1997-03-05 Pittway Corporation Vorrichtung und Verfahren zur Vorverarbeitung von Signalen

Cited By (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6879253B1 (en) * 2000-03-15 2005-04-12 Siemens Building Technologies Ag Method for the processing of a signal from an alarm and alarms with means for carrying out said method
DE10046992C1 (de) * 2000-09-22 2002-06-06 Bosch Gmbh Robert Streulichtrauchmelder
US7602304B2 (en) 2002-09-19 2009-10-13 Honeywell International Inc. Multi-sensor device and methods for fire detection
US20060181407A1 (en) * 2002-09-19 2006-08-17 Tice Lee D Multi-sensor device and methods for fire detection
US20060192670A1 (en) * 2002-09-19 2006-08-31 Tice Lee D Multi-sensor device and methods for fire detection
US7068177B2 (en) * 2002-09-19 2006-06-27 Honeywell International, Inc. Multi-sensor device and methods for fire detection
US7551096B2 (en) * 2002-09-19 2009-06-23 Honeywell International Inc. Multi-sensor device and methods for fire detection
US20040189461A1 (en) * 2002-09-19 2004-09-30 Tice Lee D. Multi-sensor device and methods for fire detection
US20100039645A1 (en) * 2007-03-09 2010-02-18 Xtralis Technologies Ltd Method and system for particle detection
US8378808B1 (en) 2007-04-06 2013-02-19 Torrain Gwaltney Dual intercom-interfaced smoke/fire detection system and associated method
US20090009345A1 (en) * 2007-07-03 2009-01-08 Conforti Fred J System and method for an optical particle detector
US7847700B2 (en) 2007-07-03 2010-12-07 Conforti Fred J System and method for an optical particle detector
US20110018726A1 (en) * 2008-10-03 2011-01-27 Universal Security Instruments, Inc. Dynamic Alarm Sensitivity Adjustment and Auto-Calibrating Smoke Detection
US8284065B2 (en) 2008-10-03 2012-10-09 Universal Security Instruments, Inc. Dynamic alarm sensitivity adjustment and auto-calibrating smoke detection
US20100085199A1 (en) * 2008-10-03 2010-04-08 Universal Security Instruments, Inc. Dynamic Alarm Sensitivity Adjustment and Auto-Calibrating Smoke Detection
US8766807B2 (en) 2008-10-03 2014-07-01 Universal Security Instruments, Inc. Dynamic alarm sensitivity adjustment and auto-calibrating smoke detection
EP2244236A1 (de) 2009-04-23 2010-10-27 Honeywell International Inc. Ansaugender Rauchmelder mit variabler Geschwindigkeit
US8395501B2 (en) 2010-11-23 2013-03-12 Universal Security Instruments, Inc. Dynamic alarm sensitivity adjustment and auto-calibrating smoke detection for reduced resource microprocessors
US20140145851A1 (en) * 2011-02-21 2014-05-29 Fred Conforti Apparatus and method for detecting fires
RU2487416C1 (ru) * 2011-10-31 2013-07-10 Сергей Иванович Бурдюгов Адаптивный способ пожарной сигнализации
US20140062705A1 (en) * 2012-08-30 2014-03-06 Honeywell International Inc. Multilevel Signaling System and Method
US9202359B2 (en) * 2012-08-30 2015-12-01 Honeywell International Inc. Multilevel signaling system and method
US9934672B2 (en) * 2015-09-24 2018-04-03 Honeywell International Inc. Systems and methods of conserving battery life in ambient condition detectors
US10769903B2 (en) * 2017-07-05 2020-09-08 Oneevent Technologies, Inc. Evacuation system
US10540871B2 (en) * 2017-07-05 2020-01-21 Oneevent Technologies, Inc. Evacuation system
US20200082682A1 (en) * 2017-07-05 2020-03-12 Oneevent Technologies, Inc. Evacuation system
US20190066464A1 (en) * 2017-07-05 2019-02-28 Oneevent Technologies, Inc. Evacuation system
US10769904B2 (en) 2017-07-05 2020-09-08 Oneevent Technologies, Inc. Evacuation system
US10777052B2 (en) 2017-07-05 2020-09-15 Oneevent Technologies, Inc. Evacuation system
US11238710B2 (en) * 2017-07-05 2022-02-01 Oneevent Technologies, Inc. Evacuation system
US11176796B2 (en) 2018-07-13 2021-11-16 Carrier Corporation High sensitivity fiber optic based detection
US11340172B2 (en) 2018-07-13 2022-05-24 Carrier Corporation Enhanced robustness for high sensitivity fiber optic smoke detection
US11948439B2 (en) 2018-07-13 2024-04-02 Carrier Corporation High sensitivity fiber optic based detection
US11936489B2 (en) 2021-02-02 2024-03-19 True Manufacturing Co., Inc. Systems, methods, and appliances that enable regional control of refrigeration appliances
US11875664B2 (en) 2021-06-04 2024-01-16 Smart Cellular Labs, Llc Integrated smoke alarm communications system

Also Published As

Publication number Publication date
DE69821671D1 (de) 2004-03-25
EP0877347A3 (de) 2000-01-19
JPH1166452A (ja) 1999-03-09
JP3973762B2 (ja) 2007-09-12
DE69821671T2 (de) 2005-01-13
EP0877347B1 (de) 2004-02-18
EP0877347A2 (de) 1998-11-11

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